Many microdevices, such as integrated circuits, have become so complex that these devices cannot be manually designed. For example, even a simple microprocessor may have millions and millions of transistors that cooperate to form the components of the microprocessor. As a result, electronic design automation tools have been created to assist circuit designers in analyzing a circuit design before it is manufactured. These electronic design automation tools typically will execute one or more electronic design automation (EDA) processes to verify that the circuit design complies with specified requirements, identify problems in the design, modify the circuit design to improve its manufacturability, or some combination thereof. For example, some electronic design automation tools may provide one or more processes for simulating the operation of a circuit manufactured from a circuit design to verify that the design will provides the desired functionality. Still other electronic design automation tools may alternately or additionally provide one or more processes for confirming that a circuit design matches the intended circuit schematic, for identifying portions of a circuit design that do not comply with preferred design conventions, for identifying flaws or other weaknesses the design, or for modifying the circuit design to address any of these issues. Examples of electronic design automation tools include the Calibre® family of software tools available from Mentor Graphics Corporation of Wilsonville, Oreg.
As electronic devices continue to have smaller and smaller features and become more complex, greater sophistication is being demanded from electronic design automation tools. For example, manufacturing technology faces increasing challenges related to yield, reliability, and leakage and timing variability. These challenges have led to a host of design for manufacturability (DFM) techniques because process improvements alone are not sufficient. The early DFM applications addresse yield issues caused by random defects and catastrophic failures. These process-based, or physical, DFM solutions identify and correct design areas that are vulnerable to functional failures, such as shorts and opens. These defective design areas are often referred to as hotspots.
At 65 nm and below, parametric failures become the dominant yield-limiting mechanism. Manufacturing variations affecting power, timing, or other performance specifications cause parametric yield loss. These failure mechanisms are addressed by the next generation of DFM solutions, Electrical DFM (EDFM). One of the main functions for EDFM tools is to identify hotspots related to parametric failures. Conventional approaches utilize full chip electrical simulations along with calculation of electrical property variations for each transistor due to manufacturing variations. For a relatively small chip with 23,000 transistors, however, the electrical DC current simulation alone consumes one hour. It is desirable to have a fast hotspot detection method.